I don't mind him casting himself, because it comes from his everybody-mucks-in, just get the film made style, plus he usually picks very small roles and can be effective surrounded by the heavyweights. His verbal attack on Jules in Pulp Fiction is one of my favourite scenes ever! It works brilliantly because Jackson is humbled and Travolta is getting so pissed off and Tarantino as an actor isn't anywhere near either of them.
Jason Connery is awful and overacts every scene, reeling off each line of dialogue with the professionalism of a News of the World telephone hacker.